六、实验代码（C#）
using System;
using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text;
using System.Threading.Tasks; using System.Windows.Forms;
namespace 词法分析器
{ /*单词符号 种别码 单词符号 种别码 * if 1 标识符 40 * else 2 常量 41 * then 3 * 42
* while 4 / 43 * do 5 + 44 * begin 6 - 45 * end 7 > 46 * printf 8 < 47 * main 9 <> 48 * scanf 10 <= 49 * return 11 >= 50 * = 51 * ; * ( * ) * { * } * ++ * -- * 出错符 * # * */
public partial class Form1 : Form {
/*
*成员变量 */
String text = \
Char[] text_is;//输入流
int type_code=10;//单词种别码 int number;//整形常量 int line=1;//行号 int column = 1;//列号 char ch; int p = 0; String []keyword=new String[]{\\\ public Form1() {
InitializeComponent(); } /*
* 对输入流进行操作 */
private void readIo() {
52 53 54 55 56 57 58 -1 0 \\
text = \ try {
ch = text_is[p++]; }
catch (Exception) { ; }
/*预处理*/ while (ch == ' ') {
ch = text_is[p]; p++; }
if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) //标识符或变量名检测 {
while ((ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z'))
{
text = text + ch; ch = text_is[p++]; } p--;
type_code = 40;
for (int i = 0; i< keyword.Length; i++) //保留字检测 if (text==keyword[i]) {
type_code = i + 1; break; } }
else if ((ch >= '0' && ch <= '9')) //数字检测 {
if ((text_is[p] >= 'a' && text_is[p] <= 'z') || (text_is[p] >= 'A' && text_is[p] <= 'Z'))
{
while (ch!=' '&&ch!=';'&&ch!='#') {
text = text + ch;
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